CVE-2026-126082: Ruby on Rails Active Storage ImageMagick arbitrary file read and write

CVE-2026-126082 · Severity: critical · CVSS 9.8 · Published 2026-11-10

Rails Active Storage is a file upload system that integrates with cloud storage and database records. When using ImageMagick for image processing, an attacker can upload a specially crafted image file to read sensitive files like secret keys and credentials, or write arbitrary files to the server—potentially enabling account takeover, data theft, or remote code execution.

Vendors: Rails.

Quick answers

Is CVE-2026-126082 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-126082 being exploited in the wild.
How severe is CVE-2026-126082?
Critical severity, with a CVSS score of 9.8, published 10 November 2026.
Which products and versions are affected?
Rails before 8.1.4.1 and before 8.0.5.2.
Is there a fix for CVE-2026-126082?
Yes: fixed in Rails 8.1.4.1, 8.0.5.2. Until then: Do not configure config.active_storage.variant_processor = :mini_magick if you allow untrusted file uploads, or ensure ImageMagick is configured with a restrictive security policy (policy.xml) that denies MSL and other dangerous coders before upgrading. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-126082 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-126082?
Check whether you run Rails at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: Rails 8.1.4.1, 8.0.5.2

Do not configure config.active_storage.variant_processor = :mini_magick if you allow untrusted file uploads, or ensure ImageMagick is configured with a restrictive security policy (policy.xml) that denies MSL and other dangerous coders before upgrading.

Technical details

The vulnerability exists in Active Storage's use of ImageMagick through the MiniMagick wrapper. ImageMagick's file analyzer runs automatically when attachments are uploaded, and can be tricked via specially crafted files (e.g., SVG with MSL coder directives) to read and write arbitrary files. The vulnerability requires no authentication, variant processing, or explicit analysis call—merely uploading a malicious file triggers the vulnerability. The fix ships an ImageMagick security policy that blocks dangerous coders (MSL, others) and file indirection.

Affected products

  • Rails Rails before 8.1.4.1 and before 8.0.5.2

Timeline

  • 2026-11-10: disclosed

References

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